1. Field of the Invention
This invention generally relates to a method for controlling the winding of a winding apparatus, wherein a web is payed out from an unwinding shaft and wound up onto a winding shaft and, in particular, to a control method for winding of a slitter rewinding apparatus, wherein a wide web is slit and separated into a plurality of narrow-width webs and wound up.
2. Description of Related Art
As a winding apparatus for winding up a web payed out from an unwinding shaft onto a winding shaft, a slitter rewinder has been heretofore known and received a wide practical acceptance, wherein a wide web is slit in the elongate direction into a plurality of narrow-width webs and the narrow-width webs thus slit are separated alternately vertically (upwardly and downwardly) or longitudinally (fore and aft) and wound onto respective winding shafts disposed in upper and lower positions or in forward and rearward positions. The control of winding with such a conventional slitter rewinder, as generally illustrated in FIG. 1, is carried out in a manner that from an unwind roll R0 on an unwinding shaft, on which a brake 31 is fitted, a web W is unwound at a preset web speed under rotation of take-off rollers 20, 30 by means of a motor M2, the preset speed being set with a speed setting unit 37, the motor M2 being controlled with a control amplifier 36, wherein the tension required for the unwinding of the web is controlled by means of the brake 31 through a control amplifier 32 by matching a tension (variable) detected by means of a tension detector 35 fitted on an unwinding roller 1 with a definite unwinding tension set by means of an unwinding tension setting unit 34 on a computing unit 33.
The web thus unwound by means of the take-off rollers 20, 30 is slit with a slitter blade 4 into a plurality of narrow-width webs, which are in turn wound via touch rollers 5 onto respective winding shafts of a wind-up roll R1. At that time, the winding operation is controlled by multiplying a movement distance (variable) of the touch roller 5 detected with a roll radius detector 41 and a definite tension set on a tension setting unit 40 on a torque computing unit 39, transmitting a torque value thus obtained to a torque-controllable motor M1 through a control amplifier 38 for the motor, whereby to control the motor M1. In FIG. 1, only one winding shaft is indicated for simplicity.
Stated another way, the conventional control method for winding has been conducted by disposing the brake (31) at an unwinding position, the motor (M2) for driving the take-off rollers at a take-off position, and the motor (M1) capable of controlling torque at a winding position, in combination.
However, the take-off rollers at the take-off position are required to tension the web at the unwinding position by a suitable tension force, which necessitates satisfying a variety of important conditions involving complicated factors such as a friction force between the web and the roller surface, a web embracing amount of each of the take-off rollers, the number of take-off rollers installed, etc.
Further, the take-off position is tensioned under a tension necessary for winding of the web from the winding position, but such a web take-off roller unit that is free from being dragged by the tension is required.
In the conventional control system, it is thus necessary and indispensable that the web be tensioned by a necessary tension and the take-off roller unit do not slip even if tensioned from the winding position.
In order to grapple with the problems mentioned above, this invention has been made by investigating particularly into a drive system of a winding apparatus, and it is an object of this invention to do away with the need of the aforesaid take-off roller unit and its drive device at the take-off position by providing free rotating guide rollers that are necessary in a minimum number for the winding or slitting-rewinding of a web and accordingly, to shorten a distance between the unwinding shaft and the winding shaft, thereby downsizing the winding apparatus and enabling a significant cost reduction.